Zhang Yuanyuan, Wang Yuqi, Wei Youheng, Ma Jian, Peng Jingtao, Wumaier Reziya, Shen Suqin, Zhang Pingzhao, Yu Long
State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, Shanghai 200433, PR China.
Department of Urology, Shanghai First People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200080, PR China.
Biochem Biophys Res Commun. 2015 Mar 13;458(3):494-500. doi: 10.1016/j.bbrc.2015.01.136. Epub 2015 Feb 7.
Centrosome linker tethers interphase centrosomes together allowing them to function as a single microtubule organization center. The centrosome linker is disrupted at the onset of mitosis to ensure timely centrosome disjunction and bipolar spindle formation and is reassembled at the end of mitosis. While the mechanism controlling centrosome linker disassembly at early mitosis has been well explored, little is known about how the linker is subsequently reassembled before mitotic exit. Here we report that ASPP1 and ASPP2, two members of the apoptosis stimulating proteins of p53 (ASPP) family, are involved in centrosome linker reassembly. We showed that ASPP1/2 interacted with centrosome linker protein C-Nap1. Co-depletion of ASPP1 and ASPP2 inhibited re-association of C-Nap1 with centrosome at the end of mitosis. Moreover, ASPP1/2 facilitated the interaction between C-Nap1 and PP1α, and this interaction was significantly reduced by co-depletion of ASPP1/2. ASPP1/2 antagonized the NEK2A-mediated C-Nap1 Ser2417/2421 phosphorylation in a PP1-dependent manner. Co-depletion of ASPP1 and ASPP2 inhibited dephosphorylation of C-Nap1 (Ser2417/2421) at the end of mitosis. Based on these findings, we propose that ASPP1/2 act as PP1-targeting subunits to facilitate C-Nap1 dephosphorylation and centrosome linker reassembly at the end of mitosis.
中心体连接子将间期中心体栓系在一起，使其能够作为单个微管组织中心发挥作用。在有丝分裂开始时，中心体连接子会被破坏，以确保中心体及时分离和双极纺锤体形成，并在有丝分裂结束时重新组装。虽然在有丝分裂早期控制中心体连接子解体的机制已得到充分研究，但对于连接子在有丝分裂退出前如何随后重新组装却知之甚少。在这里，我们报告p53凋亡刺激蛋白（ASPP）家族的两个成员ASPP1和ASPP2参与了中心体连接子的重新组装。我们表明ASPP1/2与中心体连接子蛋白C-Nap1相互作用。在有丝分裂结束时，ASPP1和ASPP2的共同缺失抑制了C-Nap1与中心体的重新结合。此外，ASPP1/2促进了C-Nap1与PP1α之间的相互作用，而ASPP1/2的共同缺失显著降低了这种相互作用。ASPP1/2以PP1依赖的方式拮抗NEK2A介导的C-Nap1 Ser2417/2421磷酸化。在有丝分裂结束时，ASPP1和ASPP2的共同缺失抑制了C-Nap1（Ser2417/2421）的去磷酸化。基于这些发现，我们提出ASPP1/2作为靶向PP1的亚基，以促进有丝分裂结束时C-Nap1的去磷酸化和中心体连接子的重新组装。
